The detection of pathogens or toxins in samples is highly relevant, e.g. for clinical or security applications. Thus it is often desirable to be able to detect a certain pathogen and/or toxin in a sample within a short period of time.
A plurality of detection methods based on the use of antibodies directed against the pathogen and/or toxin are known in the state of the art. Antibodies are therefore often used since they generally display a high binding constant for their antigen and thus achieve a high specificity. Furthermore, antibodies can be generated for almost any number of antigens, i.e. e.g. pathogens or toxins.
Nevertheless, a cross-reactivity is always problematic in the use of antibodies, i.e. an unspecific binding to undesired targets. Accordingly, in the use of antibody-based detection methods also binding reactions of the antibodies to molecules not corresponding to the actual antigens of the antibodies always occur. Thus, the detection of so-called false positive antigens often takes place. Moreover, a binding to the substrate is often observed of antigens not corresponding to the antigens to be detected, however which are detected by the subsequent detection method. For example, on contacting antibody-coated magnetic beads with a sample, antigens found in the sample, like e.g. phylogenetically related pathogens, also always bind to the beads themselves and not to the antibodies bound thereto. In the subsequent detection reaction these antigens, which are actually not to be detected, then are in part also identified as false positives, or as “background” hamper the detection of the antigens really to be detected.